MailGun Route to POST to a REST API with custom header

Question

I am using Route settings of MailGun to send the mails to desired end points. There are 2 routes setup,
1. to a email id
2. to an API end point
Both of the things work as expected.
Question is,
The API end point requires some custom header to be sent. How can I configure MailGun Route, to send custom header?

Answer 1

Well, found that its not possible. It can only do a GET.